452 BRITISH PALAXOZOIC FOSSILS. [Bracuiopopa. 
Position and Locality.—Rare in the black, also in the grey, carboniferous limestone of Derbyshire; not 
very uncommon in the shelly masses of lower carboniferous limestone of Berwick-on-‘T'weed, where the frag- 
mentary specimens may be recognised by the medial ridge from the beak of the receiving valve, &c. 
LertmNA (Strophomena) PELARGONATA (Schlot. Sp.) 
Ref. and Syn. = Terebratulites pelargonatus Schlot. Akad. Minch. Vol. VI. t. 8. f. 21, 24 = Streptorhynchus 
id. King, Perm. Foss. t. 10. f. 18 to 28. 
Dese.—Semiconical, hinge-line slightly less than the width of the shell, which is greatest a little in 
front of the middle; cardinal angles slightly obtuse. Receiving valve semiconical ; beak large, elevated, so that 
the profile, from its apex to the front margin, slopes irregularly without distinct arching; beak irregularly 
inclined sometimes to the right, sometimes to the left hand, and sometimes sigmoidally; sides sloping rather 
rapidly ; surface rendered irregular by one or two concentric, wide, concave irregularities of growth ; cardinal 
area triangular, its height varying from one half to two-thirds the width of the shell; pseudo-deltidium strongly 
defined, very convex externally. Entering valve subquadrate, convex, more regular than the receiving valve, 
indented by a deep, wide, mesial hollow from the beak (which is often scarcely visible in the receiving valve) ; 
cardinal area very narrow, linear, or obsolete. Surface of both valves marked with numerous, subangular, sub- 
equal, longitudinal strize, divaricatingly arched on the sides, each branched two or three times between the 
beak and margin, where they are irregular in size, and averaging thirteen in the space of one line, at two lines 
from the beak (about the same in same space at one line from the beak), crossed by rather strong concentric 
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strize. Average length of receiving valve five lines, proportional width =, length of entering valve =, depth of 
receiving valve ;;, to =, depth of entering valve =. 
Internal casts of entering valve shew two thick, very diverging dental lamellze, extending one-third the 
length of the shell. The apex of the beak of receiving valve in all the specimens I have examined is broken, so 
that I am uncertain whether there is an apical foramen or not. Professor King’s figures represent the striation 
as considerably too coarse. It is rather coarser in the foreign than in the British specimens; averaging in 
the former eight or nine ridges in the space of one line at margin of large specimens. The specimens col- 
lected by Professor Sedgwick, and called in his paper Spirifer minutus by Mr Sowerby, supposed by Pro- 
fessor King to belong to this species, are unfortunately not in the collection. 
Position and Locality—Not uncommon in the Permian magnesian limestone of Humbleton Hill. 
Leprana (Strophomena) sENILIS (Phill. Sp.) 
Ref. and Syn. = Spirifera senilis Phill. Geol. York. t. 9. f. 5. 
Desc.—Semiconical, hinge-line slightly less than the width of the shell, forming almost rectangular car- 
dinal angles; lateral margins slightly convex, gradually blending with the more rounded front, the entire edge 
being approximately in one horizontal plane. Receiving valve irregularly semiconic; beak very large, but not 
incurved, usually inclined obliquely to one side, and so much elevated that the profile is very little arched, 
sloping gradually from the apex to the front margin, except at the step-like interruptions, produced by two or 
three very large irregular concentric undulations or interruptions of growth, which give a very irregular aspect 
to the shell; cardinal area slightly concave, inclining backwards from the plane of the margins at an angle of 
from 95° to 125°, its height varying from one-half to one-third the width of the hinge-line ; pseudo-deltidium 
very prominent, convex, the height exceeding the width at base by one-third to one-half in different specimens. 
Entering valve more evenly convex than the receiving one, and less distorted by the large concentric inter- 
ruptions of growth; profile regularly arched, greatest depth about the middle ; cardinal area linear, obsolete. 
Surface of both valves marked with narrow filiform strize (averaging four in two lines at six lines from the beak) 
in the broad flat spaces between which are developed, first one, then three, and towards the margin five, the 
additional ones being very fine at first, but towards the margin gradually nearly equalling the others in size, or 
